feat(core): add support for gemini-3.8-flash as default flash model by mr8lu · Pull Request #29172 · google-gemini/gemini-cli

mr8lu · 2026-09-02T22:31:02Z

Summary

Registers gemini-3.5-flash-lite, gemini-3.6-flash, gemini-3.7-flash, and gemini-3.8-flash as valid, selectable Gemini models (constants, VALID_GEMINI_MODELS, defaultModelConfigs.ts aliases/definitions/resolutions).
Promotes gemini-3.8-flash to the default flash model returned once the flash GA rollout experiment (hasGemini35FlashGAAccess) is active, replacing gemini-3.5-flash in that role.
Preserves explicit manual selection of any of the 3.5/3.6/3.7/3.8 flash models — they no longer get silently redirected to the default flash model.

Test plan

npx tsc --noEmit (core + cli) passes
npm run lint passes with zero warnings
Full models.test.ts, defaultModelConfigs, modelConfigService.test.ts, config.test.ts, coreToolsModelSnapshots.test.ts, and availability/* suites pass (480 tests)
Regenerated docs/reference/configuration.md and schemas/settings.schema.json from the updated model configs

🤖 Generated with Claude Code

google-cla · 2026-09-02T22:31:07Z

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github-actions · 2026-09-02T22:31:20Z

📊 PR Size: size/L

Lines changed: 613
Additions: +563
Deletions: -50
Files changed: 10

gemini-code-assist · 2026-09-02T22:33:54Z

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request expands the available Gemini model repertoire by registering several new flash variants and updating the default flash model target to gemini-3.8-flash for eligible users. The changes include updates to core configurations, CLI UI components, and test suites to ensure consistent behavior and support for these new models while maintaining existing manual selection capabilities.

Highlights

New Model Support: Added support for gemini-3.5-flash-lite, gemini-3.6-flash, gemini-3.7-flash, and gemini-3.8-flash.
Default Model Promotion: Promoted gemini-3.8-flash as the default flash model for users with GA access, replacing gemini-3.5-flash.
Manual Selection Preservation: Ensured that explicit manual selection of specific flash models is preserved and not subject to silent redirection.

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gemini-code-assist

Code Review

This pull request updates the default Gemini Flash model from gemini-3.5-flash to gemini-3.8-flash across configuration files, schemas, tests, and UI components, and registers several new Gemini 3.x Flash models. The review feedback correctly identifies that the alternative name for the 3.5 Flash model (SECONDARY_GEMINI_3_5_FLASH_MODEL / 'gemini-3-flash') was omitted from the override exclusion check in resolveModel, which would cause manual selections of this model to be overridden. It is recommended to update this check and add a corresponding test case using hardcoded literal values to prevent regressions.

gemini-code-assist · 2026-09-02T22:35:36Z

+    normalizedModel !== PREVIEW_GEMINI_FLASH_MODEL &&
+    normalizedModel !== DEFAULT_GEMINI_3_5_FLASH_MODEL &&
+    normalizedModel !== GEMINI_3_5_FLASH_LITE_MODEL &&
+    normalizedModel !== GEMINI_3_6_FLASH_MODEL &&
+    normalizedModel !== GEMINI_3_7_FLASH_MODEL &&
+    normalizedModel !== GEMINI_3_8_FLASH_MODEL


The alternative name for the 3.5 Flash model (SECONDARY_GEMINI_3_5_FLASH_MODEL / 'gemini-3-flash') is not excluded from the override check. This causes explicit manual selections of 'gemini-3-flash' to be silently redirected to gemini-3.8-flash when useGemini3_5Flash is active, violating the goal of preserving explicit manual selections of 3.5/3.6/3.7/3.8 flash models.

normalizedModel !== PREVIEW_GEMINI_FLASH_MODEL && normalizedModel !== DEFAULT_GEMINI_3_5_FLASH_MODEL && normalizedModel !== SECONDARY_GEMINI_3_5_FLASH_MODEL && normalizedModel !== GEMINI_3_5_FLASH_LITE_MODEL && normalizedModel !== GEMINI_3_6_FLASH_MODEL && normalizedModel !== GEMINI_3_7_FLASH_MODEL && normalizedModel !== GEMINI_3_8_FLASH_MODEL

gemini-code-assist · 2026-09-02T22:35:36Z

+    expect(
+      resolveModel(
+        DEFAULT_GEMINI_3_5_FLASH_MODEL,
+        false,
+        false,
+        true,
+        undefined,
+        true,
+      ),
+    ).toBe(DEFAULT_GEMINI_3_5_FLASH_MODEL);


Add a test case to verify that explicit manual selections of the alternative 3.5 Flash model name ('gemini-3-flash') are preserved and not overridden when useGemini3_5Flash is active. In accordance with our testing guidelines, use hardcoded literal values instead of importing constants to ensure tests are self-contained and less brittle.

Suggested change

expect(

resolveModel(

DEFAULT_GEMINI_3_5_FLASH_MODEL,

false,

false,

true,

undefined,

true,

),

).toBe(DEFAULT_GEMINI_3_5_FLASH_MODEL);

expect(

resolveModel(

'gemini-3.5-flash',

false,

false,

true,

undefined,

true,

),

).toBe('gemini-3.5-flash');

expect(

resolveModel(

'gemini-3-flash',

false,

false,

true,

undefined,

true,

),

).toBe('gemini-3-flash');

References

In tests, prefer using hardcoded literal values instead of importing constants to ensure tests are self-contained and less brittle.

wissamblue69-dotcom · 2026-09-03T01:48:29Z

Summary

Registers gemini-3.5-flash-lite, gemini-3.6-flash, gemini-3.7-flash, and gemini-3.8-flash as valid, selectable Gemini models (constants, VALID_GEMINI_MODELS, defaultModelConfigs.ts aliases/definitions/resolutions).

Promotes gemini-3.8-flash to the default flash model returned once the flash GA rollout experiment (hasGemini35FlashGAAccess) is active, replacing gemini-3.5-flash in that role.

Preserves explicit manual selection of any of the 3.5/3.6/3.7/3.8 flash models — they no longer get silently redirected to the default flash model.

Test plan

npx tsc --noEmit (core + cli) passes

npm run lint passes with zero warnings

Full models.test.ts, defaultModelConfigs, modelConfigService.test.ts, config.test.ts, coreToolsModelSnapshots.test.ts, and availability/* suites pass (480 tests)

Regenerated docs/reference/configuration.md and schemas/settings.schema.json from the updated model configs

🤖 Generated with Claude Code

…rollout SECONDARY_GEMINI_3_5_FLASH_MODEL ('gemini-3-flash') was missing from the override-exclusion list in resolveModel(), so explicitly selecting it while the flash GA rollout is active silently redirected to the default flash model instead of preserving the user's choice, same as the other flash aliases.

gemini-cli · 2026-09-10T01:44:38Z

Hi there! Thank you for your interest in contributing to Gemini CLI.

To ensure we maintain high code quality and focus on our prioritized roadmap, we only guarantee review and consideration of pull requests for issues that are explicitly labeled as 'help wanted'.

This PR will be closed in 7 days if it remains without that designation. We encourage you to find and contribute to existing 'help wanted' issues in our backlog! Thank you for your understanding.

gemini-cli · 2026-09-17T01:48:17Z

This pull request is being closed as it has been open for 14 days without a 'help wanted' designation. We encourage you to find and contribute to existing 'help wanted' issues in our backlog! Thank you for your understanding.

feat(core): add support for gemini-3.8-flash as default flash model

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mr8lu requested review from a team as code owners September 2, 2026 22:31

github-actions Bot added the size/l A large sized PR label Sep 2, 2026

gemini-code-assist Bot reviewed Sep 2, 2026

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gemini-cli Bot added the status/need-issue Pull requests that need to have an associated issue. label Sep 2, 2026

wissamblue69-dotcom approved these changes Sep 3, 2026

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github-actions Bot mentioned this pull request Sep 3, 2026

📊 AI CLI 工具社区动态日报 2026-09-03 96loveslife/big_model_radar#430

Open

mr8lu force-pushed the feat/support-gemini-3.8-flash branch from 0a7e0c0 to 5aec0a2 Compare September 4, 2026 02:02

github-actions Bot mentioned this pull request Sep 4, 2026

📊 AI CLI 工具社区动态日报 2026-09-04 96loveslife/big_model_radar#435

Open

This was referenced Sep 5, 2026

v0.55.1: any --model gemini-<X.Y>-flash is silently served by gemini-3.5-flash, including versions that do not exist #28859

Closed

Enterprise Gemini CLI users were promised access to the latest models — so where are Gemini 3.5 Flash and 3.6 Flash? #28625

Open

gemini-cli Bot added the status/pr-nudge-sent label Sep 10, 2026

github-actions Bot mentioned this pull request Sep 10, 2026

📊 AI CLI 工具社区动态日报 2026-09-10 96loveslife/big_model_radar#466

Open

gemini-cli Bot closed this Sep 17, 2026

github-actions Bot mentioned this pull request Sep 17, 2026

📊 AI CLI 工具社区动态日报 2026-09-17 96loveslife/big_model_radar#502

Open

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feat(core): add support for gemini-3.8-flash as default flash model - #29172

feat(core): add support for gemini-3.8-flash as default flash model#29172
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